HTC leads the way in the field in the US, holding a 60 percent share of 4G customers. Verizon Wireless is the top provider in the territory, claiming that it now provides coverage from more than half of North America.

Apple has previously expressed reluctance about entering the LTE market. While announcing the company's quarterly results in April, CEO Tim Cook said that such handsets "force a lot of design compromises" the firm is not willing to make.

Recent figures from ABI Research suggest that the number of 4G handsets in circulation will rise to 245 million in 2016. Just 4.6 million were shipped last year.